(1)
Sir
Isaac Newton (2) Sir
Isaac Newton and the Unification of Physics & Astronomy|Back to astronomy || Go to lesson 1 || Go to lesson 2 || Go to lesson 3 || Go to lesson 4 || Go to lesson 5 || Go to page 6 || Go to lesson 7 || The End ||
Tahsiri: Lecture notes :
Kenealy: Read chapters (1-6).
Please click on the
Virtual library www reference guides after the red arrow for further Discussions and Illustrations on the important
terms relevant to my lectures.
* By Newton's time, work by Galileo, Kepler, Descartes, Hooke, and others had led to an understanding of inertial motion and the need for a central force to account for the curved paths of the planets around the Sun.
a) Illustrations(1)
Sir
Isaac Newton (2) Sir
Isaac Newton and the Unification of Physics & Astronomy
* Newton's law of inertia says that the momentum of an object
remains constant unless it is acted on by an unbalanced force.
The momentum of an object is the product of its mass and velocity.
* Newton's law of force says that when a force acts on a body, it causes a change in its momentum in the direction in which the force is applied. Usually, the law of force is expressed as F = ma.
* Newton's law of action and reaction says that when one body exerts a force on a second body, the second body exerts a force on the first equal in magnitude but opposite in direction.
b) Illustrations(1)
Newto's three
Laws (2) Newton's
second law (3) Newton's
Laws
* Newton's law of universal gravitation states that every
two particles of matter attract each other with a force that depends
on the product of their masses and varies inversely with the square
of the distance between them. The law of gravitation is expressed
as F = GMm/d^2.
c) Illustrations(1)
Newton's
universal law of gravity (2) Newton's
Law of Universal Gravitation (3) Newton's
law of gravity (4) Newton's
law of gravity with quiz (5) Calculation
on gravity (6) Newton's
laws and the law of gravity (7) Law
of gravity
* Angular momentum is the momentum associated with rotation
or revolution. Angular momentum can be transferred from one object
to another or redistributed. However, it is always conserved.
d) Illustrations(1)
Consevation
of angular momentum (2) Angular
momentum () Conservation
of angular momentum
* Newton found that orbiting objects attracted to the Sun
by the force of gravity obey Kepler's laws. He discovered a general
form of Kepler's third law relating the separation, orbital period,
and masses of any two orbiting bodies. This relationship is the
basis of most astronomical mass determinations.
e) Illustrations(1)
Kepler's
third law (2) Kepler's
law tutorial (3) Newton's
law and Kepler's law (4) Kepler's
second law animation (5) Problems
for Kepler's law (6) Kepler's
law activity
* Circular speed is the orbital speed of a body that moves
in a circular orbit. The circular speed at a given orbital distance
has the same value as the average orbital speed for an elliptical
orbit having a semi-major axis equal to the circular distance.
f) Illustrations(1)
Circular
speed (2) Circular
speed (3) Orbital
speed
* A body moving at escape velocity leaves the solar system
on a parabolic path and never returns. At any distance from the
Sun, escape velocity is the square root of 2 times the circular
speed at that distance.
g) Illustrations(1)
Escape
velocity (2) Escape
velocity demo (3) Escape
velocity (4) Escape
velocity calculation
* Tidal forces are differences in gravitational force. They
occur because the various parts of a body are in different directions
and at different distances from the object attracting them. Tidal
forces stretch the body in the direction toward and away from
the attracting object. The strongest tidal forces are felt by
large bodies near massive attractors.
h) Illustrations(1)
Tidal
force (2) Tidal
forces (3) Tides
(4) Explain
Tides (5) Tides
simulations
1. An object slows down in such a way that its acceleration is constant. What can we say about the force acting on the object? the force acting on it is constant
2. Suppose an object moves in a circular path at constant speed.
What can be said about the force acting on it the force acting
on it has constant strength
3. A mass of 50 grams is acted on by a force of 200 dynes. The
motion of the object subsequently will beacceleration at a rate
of 4 cm/sec/sec.
4. When a force is applied to a body with a mass of 10 kg, the
acceleration of the body is 1 m/s/s. If the same force is applied
to a body with a mass of 40 kg, what is the acceleration of the
body? 0.25 m/s/s
5. The force required to keep an object in a circular orbit is
directed toward the center of the circle
6. If the masses of the sun and Earth each were tripled, the force
of gravity between them would go up by nine times
7. Suppose there is a planetary system in which a planet with
an average distance of 6 AU from the star has an orbital period
of 3 years. What is the mass of the star? 24 solar masses
8. A comet has a speed which is slightly smaller than escape velocity.
What path around the sun will the comet follow? an ellipse
9. Why does the Earth have a tidal bulge on the side of the Earth
which is opposite the moon. Lunar gravity is weakest there
10. As a consequence of tides the day is lengthening, the month
lengthening 4. When a force is applied to a body with a mass of
10 kg, the acceleration of the body is 1 m/s/s. If the same force
is applied to a body with a mass of 40 kg, what is the acceleration
of the body ? 0.25 m/s/s
5. The force required to keep an object in a circular orbit is
directed toward the center of the circle
6. If the masses of the sun and Earth each were tripled, the force
of gravity between them would go up by nine times
7. Suppose there is a planetary system in which a planet with
an average distance of 6 AU from the star has an orbital period
of 3 years. What is the mass of the star?
24 solar masses
8. A comet has a speed which is slightly smaller than escape velocity.
What path around the sun will the comet follow? an ellipse
9. Why does the Earth have a tidal bulge on the side of the Earth
which is opposite the moon? lunar gravity
is weakest there
10. As a consequence of tides. the day is lengthening, the
month lengthening
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